Apparatus for jetting droplet and apparatus for jetting droplet using nanotip

ABSTRACT

The present invention provides a droplet jetting apparatus which jets fluid in a droplet shape. The apparatus includes a main body ( 100 ), which has a chamber ( 110 ) for containing fluid. The main body further has at least one nozzle ( 120 ) which communicates with the chamber and jets a droplet onto a printable matter, and a first electrode ( 130 ) which is formed on the inner surface of at least one selected from between the nozzle and the chamber by patterning treatment to make electrical contact with the fluid. The apparatus further includes a second electrode ( 140 ), which is provided between the nozzle and the printable matter and has a through hole, through which the droplet is jetted from the nozzle onto the printable matter, a power supply ( 200 ) which supplies a voltage applied between the first electrode and the second electrode, and a control unit ( 300 ) which controls the power supply.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. Ser. No. 12/993,611 with afiling date of Nov. 19, 2010, which is the national stage entry ofInternational Patent Application No, PCT/KR2008/004676 having a filingdate of Aug. 12, 2008, which claims the filing benefit of Korean PatentApplication Numbers 10-2008-0066309 and 10-2008-0066310 having filingdates of Jul. 9, 2008.

TECHNICAL FIELD

The present invention relates, in general, to apparatuses for jettingdroplets and apparatuses for jetting droplets using nanotips and, moreparticularly, to a droplet jetting apparatus which applies an electricfield (electrostatic field) to the surface of fluid discharged from anozzle, thus finely and efficiently jetting the fluid in a dropletshape, and a droplet jetting apparatus using a nanotip which applies anelectric field (electrostatic field) to the surface of fluid dischargedfrom a pointed end of the nanotip, thus finely and efficiently jettingthe fluid in a droplet shape.

BACKGROUND ART

Generally, droplet jetting apparatuses for jetting (discharging) fluidin droplet shapes have been widely used in ink jet printers and recentlyare being developed to be applied to high value-added productionindustries, such as display production processing equipment, printedcircuit board production processing equipment and DNA chip productionprocessing equipment.

In ink jet printers, ink jetting apparatuses for jetting ink intodroplet shapes are classified into a thermal-actuation type and anelectrostatic type.

First, as shown in FIGS. 1 and 2, a thermal-actuation type ink jettingapparatus includes a manifold 22 which is provided on a base plate 10,an ink channel 24 and an ink chamber 26 which are defined by partitions14 provided on the base plate 10, a heater 12 which is provided in theink chamber 26, and a nozzle 16 which is formed in a nozzle plate 18 tojet an ink droplet 29′. A thermal-actuation type ink jetting apparatushaving the above construction jets the ink droplet 29′ through thefollowing operation.

The heater 12 generates heat using voltage applied thereto. Ink 29 thatis contained in the ink chamber 26 is heated by the heat, so that abubble 28 is created.

The created bubble 28 is continuously expanded, thus applying pressureto the ink 29 contained in the ink chamber 26. Hence, a droplet 29′ isjetted to the outside through the nozzle 26.

Thereafter, ink 29 is supplied from the manifold 22 into the ink chamber26 through the ink channel 22, thus recharging the ink chamber 26.

However, in the thermal-actuation type ink jetting apparatus, ink 29 maybe chemically deformed by heat generated from the heater 12 for thepurpose of creating bubbles, with the result that the quality of the ink29 deteriorates.

Furthermore, while a droplet 29′ of ink jetted from the nozzle 16 movestowards the material to be printed on, such as paper, the droplet 29′may rapidly vary in volume due to the heat of the heater 12, thusreducing the printing quality, for example, reducing the resolution.

In addition, the thermal-actuation type ink jetting apparatus isproblematic in that it is very difficult to minutely control, forexample, the shape and size of the droplet 29′ jetted from the nozzle16.

As well, due to the above-mentioned problems, it is not easy to realizea highly integrated droplet jetting apparatus.

Meanwhile, FIGS. 3 and 4 illustrate an electrostatic droplet jettingapparatus which uses an electric field, unlike the above droplet jettingapparatus.

As shown in FIGS. 3 and 4, the electrostatic droplet jetting apparatusincludes a base electrode 32 and an opposite electrode 33 which faceeach other. Ink 31 is injected between the two electrodes 32 and 33. ADC power supply 34 is connected to the two electrodes 32 and 33.

When voltage is applied to the electrodes 32 and 33 by the DC powersupply 34, an electrostatic field is formed between the two electrodes32 and 33.

Then, Coulomb's force is applied to the ink 31 in the direction towardthe opposite electrode 33.

Meanwhile, because of the surface tension and viscosity of the ink, aforce repulsive to Coulomb's force is generated on the ink 31, so thatthe ink 31 is not easily jetted towards the electrode 33.

Therefore, to separate a droplet from the surface of the ink 31 and jetthe droplet, a relatively high voltage, for example, 1 kV or more, mustbe applied between the electrodes 32 and 33.

Furthermore, if high voltage is not applied between the electrodes 32and 33, droplets are irregularly jetted and a certain portion of the ink31 is partially heated.

In detail, a temperature T1 of ink 31′ in an area S1 becomes higher thana temperature T0 of ink 31 in an area other than the area S1. Thus, theink 31′ in the area S1 is expanded and the electrostatic field isfocused on this area, so that lots of electrons collect there.

Therefore, repulsive force applied between electrons and Coulomb's forceattributable to the electrostatic field are applied to the ink 31′ inthe area S1. Thus, as shown in FIG. 4, a droplet is separated from theink 31′ in the area S1 and moves towards the opposite electrode 33.

However, the electrostatic droplet jetting apparatus having theabove-mentioned construction is problematic in that very high voltage,for example, 1 kV or more, must be applied to the electrodes 32 and 33and the separate opposite electrode 33 must be provided at a positionfacing the nozzle. Furthermore, there is a technical limit in therealization of nano-scale patterning, which has been recently regardedas important. Recently, as the size of a device is reduced from amicro-scale to a nano-scale level, the manufacture of a nano-scalestructure becomes more important. As the results of research intoprinting techniques for patterning nano-scale structures, there haveresulted an atomic-force microscope (AFM) based method, a nanopipetdeposition method, a beam-based method, a contact printing method and anelectric radiation method. The above-mentioned methods make nano-scalepatterning possible, but there are disadvantages in that the speed ofthe patterning is relatively slow and they cannot be used to patternover a large area. Hence, a rapid printing technique that can conductpatterning in both micro- and nano-scale is required.

DISCLOSURE Technical Problem

Accordingly, the present invention has been made keeping in mind theabove problems occurring in the prior art, and an object of the presentinvention is to provide a droplet jetting apparatus which applies acontrollable electrostatic field to the surface of fluid discharged froma nozzle, thus jetting the fluid in a droplet shape without causingthermal deformation, and which can minutely control the jetted dropletusing a first electrode, a second electrode and a third electrode, andto provide a droplet jetting apparatus using a nanotip which applies acontrollable electrostatic field to the surface of fluid discharged fromthe nanotip, thus jetting the fluid in a droplet shape without causingthermal deformation, and which can minutely control the jetted dropletusing a first, second and third electrode.

Technical Solution

In an aspect, the present invention provides an apparatus for jetting adroplet onto a first surface of a printable matter, comprising: a mainbody having a chamber for containing therein a predetermined amount offluid, including liquid and particles supplied from an outside, at leastone nozzle for communicating with the chamber, the nozzle jetting adroplet of the fluid contained in the chamber onto the first surface ofthe printable matter, and a first electrode formed on an inner surfaceof at least one selected from between the nozzle and the chamber bypatterning treatment to make electrical contact with the fluid; a secondelectrode provided between the nozzle and the printable matter, thesecond electrode having therein a through hole through which the dropletis jetted from the nozzle onto the first surface of the printablematter; a power supply to supply a voltage applied between the first andsecond electrodes; and a control unit to control the power supply.

The main body may include an upper plate and a lower plate which areattached to each other, wherein the lower plate may have on an uppersurface thereof: a rectangular depression for defining the chamber; alongitudinal groove extending from the rectangular depression to a frontsurface of the lower plate to form the nozzle; and a supply hole formedin the rectangular depression and extending to a lower surface of thelower plate for supplying the fluid from the outside into the chamber.

The apparatus may further comprise a third electrode disposed at aposition spaced apart from a second surface of the printable matter by apredetermined distance.

The power supply may supply a voltage to be applied between the firstelectrode and the third electrode.

The second electrode may be formed by alternately placing electrodelayers and insulation layers on top of one another.

The control unit may individually control a voltage applied between thefirst electrode and each of the electrode layers of the secondelectrode.

The voltage applied between the first electrode and the second electrodemay comprise one selected from among a DC-pulse voltage, an AC voltageand a combination of a DC voltage and an AC voltage.

Furthermore, an end of the nozzle may protrude outwards from the mainbody.

In addition, a hydrophobic film may be applied to a surface of the endof the nozzle.

Preferably, the main body may be made of a polymer material.

The nozzle may comprise a plurality of nozzles formed in the main body,the nozzles communicating with the single chamber.

In another aspect, the present invention provides an apparatus forjetting a droplet, comprising: a first electrode provided adjacent to afirst surface of a printable matter to make electrical contact withfluid; and a second electrode provided adjacent to the first surface ora second surface of the printable matter, the second electrode formingan electrostatic field along with the first electrode to jet a dropletonto the first surface of the printable matter, wherein a voltageapplied between the first electrode and the second electrode comprisesone selected from among a DC-pulse voltage, an AC voltage and acombination of a DC voltage and an AC voltage.

In another aspect, the present invention provides an apparatus forjetting a droplet using a nanotip onto a first surface of a printablematter, comprising: a main body including a cantilever having ananoplate and a nanoplate provided under a lower surface of a first endof the nanoplate, a horizontal open channel extending from a chamber,formed in a second end of the nanoplate, to the first end of thenanoplate along an upper surface of the nanoplate so that fluidcontained in the chamber is moved to the first end of the nanoplatethrough the horizontal open channel, a vertical open channel formed inone surface of the nanotip such that a first end thereof communicateswith the horizontal open channel and a second thereof extends to apointed end of the nanotip so that the fluid that is moved to the firstend of the nanoplate is moved to the pointed end of the nanotip throughthe vertical open channel, and a first electrode provided on at leastone predetermined portion to make electrical contact with the fluid; asecond electrode provided between the pointed end of the nanotip and theprintable matter, the second electrode having therein a through hole,through which a droplet of the fluid is jetted from the pointed end ontothe first surface of the printable matter; a power supply to supply avoltage to be applied between the first electrode and the secondelectrode; and a control unit to control the power supply.

The apparatus may further comprise a third electrode disposed at aposition spaced apart from a second surface of the printable matter by apredetermined distance.

The power supply may supply a voltage to be applied between the firstelectrode and the third electrode.

The second electrode may be formed by alternately placing electrodelayers and insulation layers on top of one another.

The control unit may individually control a voltage applied between thefirst electrode and each of the electrode layers of the secondelectrode.

The voltage applied between the first electrode and the second electrodemay comprise one selected from among a DC-pulse voltage, an AC voltageand a combination of a DC voltage and an AC voltage.

Furthermore, a hydrophobic film may be applied to a surface of thepointed end of the nanotip.

The cantilever may be made of a polymer material.

The main body may comprises a plurality of main bodies provided adjacentto each other to form an integrated structure, and the second electrodemay be provided between the printable matter and the pointed ends of themain bodies, with through holes formed in the second electrode atrespective positions corresponding to the pointed ends of the mainbodies.

In another aspect, the present invention provides an apparatus forjetting a droplet using a nanotip onto a first surface of a printablematter, comprising: a main body including a cantilever having ananoplate and a nanoplate provided under a lower surface of a first endof the nanoplate, a horizontal open channel extending from a chamber,formed in a second end of the nanoplate, to the first end of thenanoplate along an upper surface of the nanoplate so that fluidcontained in the chamber is moved to the first end of the nanoplatethrough the horizontal open channel, a vertical closed channel formedthrough the nanotip in a vertical direction such that a first endthereof communicates with the horizontal open channel and a secondthereof extends to a pointed end of the nanotip so that the fluid thatis moved to the first end of the nanoplate is moved to the pointed endof the nanotip through the vertical closed channel, and a firstelectrode provided on at least one predetermined portion for makingelectrical contact with the fluid; a second electrode provided betweenthe pointed end of the nanotip and the printable matter, the secondelectrode having therein a through hole, through which a droplet of thefluid is jetted from the pointed end onto the first surface of theprintable matter; a power supply to supply a voltage to be appliedbetween the first electrode and the second electrode; and a control unitto control the power supply.

The apparatus may further comprise a third electrode disposed at aposition spaced apart from a second surface of the printable matter by apredetermined distance.

The power supply may supply a voltage to be applied between the firstelectrode and the third electrode.

The second electrode may be formed by alternately placing electrodelayers and insulation layers on top of one another.

The control unit may individually control a voltage applied between thefirst electrode and each of the electrode layers of the secondelectrode.

The voltage applied between the first electrode and the second electrodemay comprise one selected from among a DC-pulse voltage, an AC voltageand a combination of a DC voltage and an AC voltage.

Furthermore, a hydrophobic film may be applied to a surface of thepointed end of the nanotip.

The cantilever may be made of a polymer material.

The main body may comprise a plurality of main bodies provided adjacentto each other to form an integrated structure, and the second electrodemay be provided between the printable matter and the pointed ends of themain bodies, with through holes formed in the second electrode atrespective positions corresponding to the pointed ends of the mainbodies.

In another aspect, the present invention provides an apparatus forjetting a droplet using a nanotip onto a first surface of a printablematter, comprising: a main body including a nanoplate having a pointedend formed by reducing a width of a first end of the nanoplate, ahorizontal open channel extending from a chamber, formed in a second endof the nanoplate, to the first end of the nanoplate along an uppersurface of the nanoplate so that fluid contained in the chamber is movedto the pointed end of the first end of the nanoplate through thehorizontal open channel, and a first electrode provided on a portion ofthe horizontal open channel for making electrical contact with thefluid; a second electrode provided between the pointed end of thenanoplate and the printable matter, the second electrode having thereina through hole, through which a droplet of the fluid is jetted from thepointed end of the nanoplate onto the first surface of the printablematter; a power supply to supply a voltage to be applied between thefirst electrode and the second electrode; and a control unit to controlthe power supply.

The apparatus may further comprise a third electrode disposed at aposition spaced apart from a second surface of the printable matter by apredetermined distance.

The power supply may supply a voltage to be applied between the firstelectrode and the third electrode.

The second electrode may be formed by alternately placing electrodelayers and insulation layers on top of one another.

The control unit may individually control a voltage applied between thefirst electrode and each of the electrode layers of the secondelectrode.

The voltage applied between the first electrode and the second electrodemay comprise one selected from among a DC-pulse voltage, an AC voltageand a combination of a DC voltage and an AC voltage.

Furthermore, a hydrophobic film may be applied to a surface of thepointed end of the nanoplate.

The nanoplate may be made of a polymer material.

The nanoplate may comprise a plurality of nanoplates provided adjacentto each other to form an integrated structure, and the second electrodemay be provided between the printable matter and the pointed ends of thenanoplates, with through holes formed in the second electrode atrespective positions corresponding to the pointed ends of thenanoplates.

DESCRIPTION OF DRAWINGS

FIGS. 1 and 2 are views showing a thermal-actuation type droplet jettingapparatus according to a conventional technique;

FIGS. 3 and 4 are views showing an electrostatic droplet jettingapparatus according to another conventional technique;

FIG. 5 is a perspective view of a main body of an apparatus for jettinga droplet having a single nozzle, according to a first embodiment of thepresent invention;

FIG. 6 is a view showing the droplet jetting apparatus of FIG. 5;

FIG. 7 is a sectional view taken along the line A-A′ of FIG. 6;

FIG. 8 is a perspective view of a main body of an apparatus for jettinga droplet having multiple nozzles, according to the first embodiment ofthe present invention;

FIG. 9 is a view showing the droplet jetting apparatus of FIG. 8;

FIG. 10 is a sectional view taken along the line B-B′ of FIG. 9;

FIG. 11 is of views illustrating an effect of a protruded nozzle of thedroplet jetting apparatus according to the first embodiment of thepresent invention;

FIG. 12 is a view showing an apparatus for jetting a droplet using ananotip, according to a second embodiment of the present invention;

FIG. 13 is a sectional view taken along the line I-I′ of FIG. 12;

FIG. 14 is a view showing an apparatus for jetting a droplet using ananotip, according to a third embodiment of the present invention;

FIG. 15 is a view showing the concept of the apparatus for jetting adroplet using the nanotip according to the present invention;

FIG. 16 is a view showing the concept of the integrated droplet jettingapparatuses using the nanotips according to the present invention;

FIG. 17 is a view showing an interface of fluid formed on a pointed endof the nanotip of the droplet jetting apparatus according to the presentinvention; and

FIG. 18 is a view showing another embodiment of an apparatus for jettinga droplet using a nanotip according to the present invention.

<Description of the elements in the drawings> 100: main body 100a: upperplate 100b: lower plate 110: chamber 120: nozzle 130: first electrode140: second electrode 142: electrode layer 144: insulation layer 150:third electrode 200: power supply 300: control unit. 400: main body 410:first electrode 420: second electrode 420h: through hole 422: electrodelayer 424: insulation layer 430: third electrode 440: cantilever 442:nanoplate 444: nanotip 444a: pointed end 450: horizontal open channel460: vertical open channel 460′: vertical closed channel 500: powersupply 600: control unit

BEST MODE

Hereinafter, preferred embodiments of the present invention will bedescribed in detail with reference to the attached drawings.

A better understanding of the present invention may be obtained throughthe following embodiments, which are set forth to illustrate, but arenot to be construed as limiting the present invention.

First Embodiment

As shown in FIG. 6, an apparatus for jetting a droplet according to afirst embodiment of the present invention includes a main body 100provided with a first electrode 130, a second electrode 140, a thirdelectrode 150, a power supply 200 and a control unit 300.

The main body has a chamber 110 therein and includes a nozzle 120 andthe first electrode 130. The chamber 110 functions to contain therein apredetermined amount of fluid including liquid and particles suppliedfrom the outside. The nozzle 120 communicates with the chamber 110 andfunctions to jet a droplet of the fluid, contained in the chamber 110,to a first surface of printable matter A. The first electrode 130 isformed on the inner surface of at least one of the chamber 110 and thenozzle 120 by patterning treatment to make electrical contact with thefluid.

The second electrode 140 is provided between the nozzle 120 and theprintable matter A and has therein a through hole 140 h, through which adroplet is jetted from the nozzle 120 to the first surface of theprintable matter A. The power supply 200 supplies voltage appliedbetween the first electrode 130 and the second electrode 140. Thecontrol unit 300 controls the power supply 200. The third electrode 150is disposed at a position spaced apart from a second surface of theprintable matter A by a predetermined distance.

First, the main body 100 will be explained in detail below.

As shown in FIGS. 5 and 6, the main body 100 has the chamber 110, whichcontains therein a predetermined amount of fluid including liquid andparticles supplied from the outside. The main body 100 includes thenozzle 120 which communicates with the chamber 110 and jets a droplet ofthe fluid, contained in the chamber 110, to the first surface of theprintable matter A, and the first electrode 130 which is formed on theinner surface of the chamber 110 by patterning treatment to makeelectrical contact with the fluid.

As one example, the main body 100 may comprise an upper plate 100 a, anda lower plate 100 b which is attached at the upper surface thereof tothe lower surface of the upper plate 100 a, as shown in FIG. 5. Arectangular depression is formed in the upper surface of the lower plate100 b to define the chamber 110 between the upper and lower plates 100 aand 100 b which are attached to each other. Furthermore, a longitudinalgroove which extends from the rectangular depression to the frontsurface of the lower plate 100 b is formed in the upper surface of thelower plate 100 b to form the nozzle 120 between the upper and lowerplates 100 a and 100 b. A supply hole 100 h, through which fluid issupplied from the outside into the chamber 110, is formed in therectangular depression and extends to the lower surface of the lowerplate 100 b.

As shown in FIGS. 6 and 9, when the nozzle 120 is formed by attachingthe lower surface of the upper plate 100 a to the upper surface of thelower plate 100 b, the end of the nozzle 120 preferably protrudesoutwards from the main body 100. Because of this shape made such thatthe end of the nozzle 120 protrudes outwards from the main body 100, arelatively large contact angle can be maintained when a liquid surfaceof fluid is formed, thus increasing the stability of the liquid surface.

FIG. 11 shows a difference between a liquid surface formed on anapparatus (a) having a nozzle formed by simply boring and a liquidsurface formed on an apparatus (b) having a protruded nozzle. Inaddition, FIG. 11 shows distribution of an electric field depending onthe shape of a liquid surface. As a curvature radius R of the liquidsurface becomes smaller, the shape of the liquid surface comes closer toa hemispheric shape. It is to be understood that as the curvature radiusR of the liquid surface becomes smaller, the intensity of the electricfield becomes increased and the electric field is focused on the centerthereof. Therefore, it is to be appreciated that the protruded nozzleprovides many advantages in the jetting of a droplet.

Furthermore, a hydrophobic film may be applied to the surface of the endof the nozzle 120. For example, a hydrophobic surface can be formed byoxygen plasma treatment or argon and oxygen ion beam treatment. As such,in the case where the hydrophobic film is applied to the surface of theend of the nozzle 120, when a droplet is jetted from the nozzle 120, theinitial meniscus of fluid can be effectively formed. In addition, eventhough droplets be repeatedly jetted, the jetting operation can bereliably conducted and the performance thereof can be increased.

Meanwhile, as shown in FIGS. 8 and 9, several nozzles 120 may be formedin the main body 100 and extend from the single chamber 110. In detail,a single rectangular depression is formed in the upper surface of thelower plate 100 b to form the chamber 110 therein, and threelongitudinal grooves which extend from the rectangular depression to thefront surface of the lower plate 100 b are formed in the upper surfaceof the lower plate 100 b to form three nozzles 120. A supply hole 100 h,through which fluid is supplied from the outside into the chamber 110,is formed in the rectangular depression and extends to the lower surfaceof the lower plate 100 b.

Here, although the first electrode 130 has been illustrated in thedescription of FIG. 5 as being formed in the inner surface of thechamber 110 by patterning to make electrical contact with fluid, firstelectrodes 130 may be formed in the inner surfaces of the respectivenozzles 120 by patterning treatment to make electrical contact withfluid, as shown in FIG. 8. Such a first electrode 130 may also be formedon the lower surface of the upper plate 100 a.

Preferably, the main body 100 is made of polymer material. Inparticular, in the case where several droplet jetting apparatuses arearranged such that they are close to each other or, as shown in FIG. 8,several nozzles 120 are connected to the single chamber 110, if the mainbody 100 is made of non-conductive polymer material, electricalinterference occurring between the droplet jetting apparatuses orbetween the nozzles 120 can be prevented.

The main body 100 may be manufactured by a PDMS (polydimethylsiloxane)molding method.

Next, the second electrode 140 and the third electrode 150 will beexplained in detail below.

As shown in FIGS. 5 and 6, the second electrode 140 is provided betweenthe nozzle 120 of the main body 100 and the printable matter A. Thethrough hole 140 h, through which a droplet jetted from the nozzle 120is applied to the first surface of the printable matter A, is formedthrough the second electrode 140.

When the power supply 200 which will be explained later provides voltageapplied between the second electrode 140 and the first electrode 130 ofthe main body 100, fluid that has been supplied into the chamber 110 isjetted through the nozzle 120 and then printed onto the printable matterA after passing through the through hole 140 h. In detail, when voltageis applied between the first electrode 130 and the second electrode 140,an electrostatic field is formed between the first electrode 130 and thesecond electrode 140, and Coulomb's force is applied to the fluid in thedirection toward the second electrode 140 which is an opposingelectrode. Hence, a droplet is jetted onto the printable matter Athrough the nozzle 120.

Here, as shown in FIGS. 7 and 10, the second electrode 140 is formed byalternately placing electrode layers 142 and insulation layers 144 ontop of one another. Voltage which is applied between the first electrode130 and each electrode layer 142 of the second electrode 140 can beindividually controlled by the control unit 300. This, will be explainedin detail in the description of the power supply 200 and the controlunit 300.

Meanwhile, as shown in FIGS. 8 and 9, in the case of the main body 100in which the several nozzles 120 are connected to a single chamber 110of the main body 100, second electrodes 140 are provided at positionscorresponding to the respective nozzles 120, such that voltage which isapplied between the first electrode 130 and each second electrode 140can be individually controlled.

As shown in FIGS. 5, 6, 8 and 9, the third electrode 150 is disposed ata position spaced apart from the second surface of the printable matterA by a predetermined distance. Voltage is also applied between the firstelectrode 130 and the third electrode 150. As such, because voltage isalso applied between the first electrode 130 and the third electrode150, Coulomb's force is further increased so that straightness of thetrajectory of the jetted droplet can be further enhanced.

Next, the power supply 200 and the control unit 300 will be explained indetail.

As shown in FIGS. 6 and 9, the power supply 200 supplies a voltage to beapplied between the first electrode 130 and the second electrode 140 andbetween the first electrode 130 and the third electrode 150. The controlunit 300 controls the power supply 200.

As stated above, the control unit 300 individually controls voltageapplied between the first electrode 130 and each electrode layer 142.Furthermore, the control unit 300 can also independently control voltageapplied between the first electrode 130 and the second electrode 140while individually controlling voltage applied between the firstelectrode 130 and each electrode layer 142.

For example, when voltage applied between the first electrode 130 and anelectrode layer 142 disposed nearest to the nozzle 120 is different fromthe voltage applied between the first electrode 130 and an electrodelayer 142 disposed farthest from the nozzle 120, the acceleration of thejetted droplet can be varied to be increased or decreased. Depending onvariation in the acceleration of jetted droplet, the quality of theprint on the printable matter A also varies. In other words, a patternformed may vary depending or: the impact force with which a dropletstrikes the printable matter A. In the case of patterning in appliedfields, such as a display, RFID, solar cell, etc., and not simple letterprinting, there may be a difference in performance depending on theuniformity of a line or waveness. Therefore, a precise control forpreventing this is required. If the velocity of jetted droplet iscontrolled, optimal printing can be expected.

Meanwhile, voltage applied between the first electrode 130 and thesecond electrode 140 may comprise one selected from among DC-pulsevoltage, AC voltage or a combination of DC and AC voltage.

When electric charges are electrically charged on the interface of fluidby the consecutive application of signals of DC voltage and the electriccharges move in the tangential direction of the interface, electrostaticforce is concentrated on the central portion of the interface, thusjetting a droplet. However, because the interface and a jetting modevary depending on the level of applied voltage and the electricalconductivity, the surface tension coefficient or the viscosity of fluid,if consecutive signals are applied, only under the restrictive conditionthat a single droplet be formed can droplets be formed and jetted.

To overcome this, if DC voltage is applied, because electrostatic forceis applied to the interface of a droplet only for a limited time, adesired number of droplets can be formed and jetted at desired point intime. In the case of continuous jet or cone-jet, a droplet can also beformed by cutting the continuous jet. However, even in this case, toeffectively form a droplet, the conditions, such as the applied voltage,must be optimally given depending on the physical characteristics of thefluid. In other words, optimal voltage and frequency pulse must beapplied depending on the characteristics of the fluid such that adesired number of droplets are formed at a desired point in time.

Meanwhile, according to recent research of electrospray, it is reportedthat the interface of fluid can also be changed by AC voltage.Therefore, in the first embodiment of the present invention, it isproposed to form and jet a droplet using AC voltage.

Moreover, to enhance the efficiency and effect of forming and jetting adroplet, preferably, DC voltage is applied within a range in which fluidis not sprayed or a droplet is not formed and, simultaneously, ACvoltage of a special frequency is applied. Then, droplets can be formedand jetted a number of times proportional to the correspondingfrequency, and more reliable optimal conditions can be given.

Second Embodiment and Third Embodiment

As shown in FIG. 12 or 14, an apparatus for jetting a droplet using ananotip according to a second or a third embodiment of the presentinvention includes a main body 400 provided with a first electrode 410,a second electrode 420, a third electrode 430, a power supply 500 and acontrol unit 600.

The main body 400 includes a cantilever 440, a horizontal open channel450, a vertical open channel 460 and the first electrode 410. Thecantilever 440 includes a nanoplate 442 and a nanotip 444, which isprovided under the lower surface of a first end of the nanoplate 442.The horizontal open channel 450 extends from a chamber (C of FIG. 15),which is formed in a second end of the nanoplate 442, to the first endof the nanoplate 442 along the upper surface of the nanoplate 442. Fluidwhich is contained in the chamber C is moved to the first end of thenanoplate 442 through the horizontal open channel 450. The vertical openchannel 460 is formed in one surface of the nanotip 444 such that afirst end thereof communicates with the horizontal open channel 450 anda second thereof extends to a pointed end 444 a of the nanotip 444.Thus, the fluid that is moved to the first end of the nanoplate 442 ismoved to the pointed end 444 a of the nanotip 444 through the verticalopen channel 460. The first electrode 410 is provided to make electricalcontact with fluid.

The second electrode 420 is provided between the pointed end 444 a ofthe nanotip 444 and the printable matter A and has therein a throughhole 420 h, through which a droplet is jetted from the pointed end 444 ato the first surface of the printable matter A. The power supply 500supplies voltage applied between the first electrode 410 and the secondelectrode 420. The control unit 600 controls the power supply 500. Thethird electrode 430 is disposed at a position spaced apart from a secondsurface of the printable matter A by a predetermined distance.

Here, a vertical closed channel 460′ may be provided in place of thevertical open channel 460. In this case, the horizontal open channel 450extends from the chamber C of the second end of the nanoplate 442 to thefirst end of the nanoplate 442 along the upper surface of the nanoplate442, and the vertical closed channel 460′ is vertically formed throughthe nanotip 444 such that a first end thereof communicates with thehorizontal open channel 450 and a second end thereof extends to thenanotip 444 a of the nanotip 444.

First, the main body 400 will be explained in detail.

The main body 400 according to the second embodiment includes acantilever 440, which has a nanoplate 442 and a nanotip 444 that isprovided under the lower surface of a first end of the nanoplate 442.The main body 400 has a horizontal open channel 450, which extends froma chamber C that is formed in a second end of the nanoplate 442 to thefirst end of the nanoplate 442 along the upper surface of the nanoplate442 so that fluid which is contained in the chamber C is moved to thefirst end of the nanoplate 442 through the horizontal open channel 450.The main body 400 further has a vertical open channel 460 which isformed in one surface of the nanotip 444 such that a first end thereofcommunicates with the horizontal open channel 450 and a second thereofextends to a pointed end 444 a of the nanotip 444 so that the fluid thatis moved to the first end of the nanoplate 442 is moved to the pointedend 444 a of the nanotip 444 through the vertical open channel 460. Themain body 400 further includes a first electrode 410 which is providedat at least one predetermined position for making electrical contactwith the fluid.

As shown in FIG. 12, in the cantilever 440 of the main body 400according to the second embodiment, for example, the horizontal openchannel 450 may be formed by forming a groove in the upper surface ofthe nanoplate 442 along the longitudinal center axis of the nanoplate442. The vertical open channel 460 may be formed by forming a groove inthe surface of the nanotip 444 along the longitudinal center axis of thenanotip 444 such that the groove of the nanotip 444 is connected to thegroove the nanoplate 442.

The first electrode 410 is formed on the inner surfaces of thehorizontal open channel 450 and the vertical open channel 460 bypatterning treatment. Here, the first electrode 410 may be formed in oneselected from between the horizontal open channel 450 and the verticalopen channel 460. Alternatively, the main body 400 may be made ofconductive material and thus itself may be used as the first electrode410.

In the case where the first electrode 410 is formed on the inner surfaceof the horizontal open channel 450 or the vertical open channel 460 bypatterning treatment, the cantilever 440 is preferably made of polymermaterial. Then, even if the several main bodies 400 are arrangedadjacent to each other, electrical interference therebetween can beprevented.

Meanwhile, in the third embodiment, the main body 400 includes acantilever 440, which has a nanoplate 442 and a nanotip 444 that isprovided under the lower surface of a first end of the nanoplate 442.The main body 400 has a horizontal open channel 450, which extends froma chamber C that is formed in a second end of the nanoplate 442 to thefirst end of the nanoplate 442 along the upper surface of the nanoplate442 so that fluid which is contained in the chamber C is moved to thefirst end of the nanoplate 442 through the horizontal open channel 450.The main body 400 further has a vertical closed channel 460′ which isvertically formed through the nanotip 444 such that a first end thereofcommunicates with the horizontal open channel 450 and a second thereofextends to a pointed end 444 a of the nanotip 444 so that the fluid thatis moved to the first end of the nanoplate 442 is moved to the pointedend 444 a of the nanotip 444 through the vertical closed channel 460′.The main body 400 further includes a first electrode 410 which isprovided at at least one predetermined position for making electricalcontact with fluid.

As shown in FIG. 14, in the cantilever 440 of the main body 400according to the third embodiment, for example, the horizontal openchannel 450 may be formed by forming a groove in the upper surface ofthe nanoplate 442 along the longitudinal center axis of the nanoplate442. The vertical closed channel 460′ may be formed by forming avertical hole through the nanotip 444 such that the vertical hole of thenanotip 444 is connected to the groove the nanoplate 442.

The first electrode 410 is formed on the inner surfaces of thehorizontal open channel 450 and the vertical closed channel 460′ bypatterning treatment. Here, the first electrode 410 may be formed in oneselected from between the horizontal open channel 450 and the verticalclosed channel 460′. Alternatively, the main body 400 may be made ofconductive material and thus itself may be used as the first electrode410.

In the case where the first electrode 410 is formed on the inner surfaceof the horizontal open channel 450 or the vertical closed channel 460′by patterning treatment, the cantilever 440 is preferably made ofpolymer material. Then, even if several main bodies 400 are arrangedadjacent to each other, electrical interference therebetween can beprevented.

Furthermore, a hydrophobic film may be applied to the surface of thepointed end 444 a of the nanotip 444. For example, a hydrophobic surfacecan be formed by oxygen plasma treatment or argon and oxygen ion beamtreatment. As such, in the case where the hydrophobic film is applied tothe surface of the end of the nozzle, when a droplet is jetted throughthe nozzle, the initial meniscus of fluid can be effectively formed. Inaddition, even if droplets are repeatedly jetted, the jetting operationcan be reliably conducted and the performance thereof can be increased.

The main body 100 may be manufactured by a PCMS (polycimethylsiloxane)molding method.

Next, the second electrode 420 and the third electrode 430 will beexplained below.

As shown in FIGS. 12 and 14, the second electrode 420 is providedbetween the pointed end 444 a of the nanotip 444 and the printablematter A and has therein a through hole 420 h, through which a dropletis jetted from the pointed end 444 a of the nanotip 444 to the firstsurface of the printable matter A.

When the power supply 500 which will be explained in detail latersupplies voltage applied between the second electrode 420 and the firstelectrode 410 of the main body 400, fluid that has been supplied intothe chamber C is jetted through the pointed end 444 a via the horizontalopen channel 450 and the horizontal closed channel 460 or the horizontalopen channel 450 and then printed onto the printable matter A afterpassing through the through hole 420 h. In detail, when voltage isapplied between the first electrode 410 and the second electrode 420, anelectrostatic field is formed between the first electrode 410 and thesecond electrode 420, and Coulomb's force is applied to the fluid in thedirection toward the second electrode 420 which is an oppositeelectrode. Hence, a droplet is jetted onto the printable matter Athrough the pointed end 444 a.

Here, as shown in FIG. 13, the second electrode 420 is formed byalternately placing electrode layers 422 and insulation layers 424 ontop of one another. Voltage which is applied between the first electrode410 and each electrode layers 422 of the second electrode 420 can beindividually controlled by the control unit 600. This will be explainedin detail, in the description of the power supply 500 and the controlunit 600.

Meanwhile, as shown in FIG. 15, in the case where a droplet is jettedfrom the single chamber C through the single pointed end 444 a, thesingle through hole 420 h is formed through the second electrode 420. Asshown in FIG. 16, several main bodies 400 are arranged adjacent to eachother to form an integrated structure, and second electrodes 420 areprovided at positions corresponding to the pointed end 442 of therespective main bodies 400, such that voltage which is applied betweenthe first electrode 410 and each second electrode 420 can beindividually controlled.

As shown in FIGS. 12, 14, 15 and 16, the third electrode 430 is disposedat a position spaced apart from the second surface of the printablematter A by a predetermined distance. Voltage is also applied betweenthe first electrode 410 and the third electrode 430. As such, becausevoltage is also applied between the first electrode 410 and the thirdelectrode 430, Coulomb's force is further increased so that straightnessof the trajectory of a jetted droplet can be further enhanced.

Below, the power supply 500 and the control unit 600 will be explainedin detail.

As shown in FIGS. 12 and 14, the power supply 500 supplies voltage whichis applied between the first electrode 410 and the second electrode 420and between the first electrode 410 and the third electrode 430. Thecontrol unit 600 controls the power supply 500.

As stated above, the control unit 600 individually controls voltageapplied between the first electrode 410 and each electrode layer 422.Furthermore, the control unit 600 can also independently control voltageapplied between the first electrode 410 and the second electrode 420 andthat applied between the first electrode 410 and each electrode layer442.

For example, when voltage applied between the first electrode 410 and anelectrode layer 442 disposed nearest to the pointed end 444 a isdifferent from voltage applied between the first electrode 410 and anelectrode layer 142 disposed farthest from the pointed end 444 a, theacceleration of jetted droplet can be positively or negativelyinfluenced. Depending on variation in the acceleration of a jetteddroplet, the quality of the print on the printable matter A is alsovaried.

Meanwhile, voltage applied between the first electrode 410 and thesecond electrode 420 may comprise one selected from among DC-pulsevoltage, AC voltage or a combination of DC and AC voltage.

When electric charges are electrically charged on the interface of fluidby the application of consecutive signals of DC voltage and the electriccharges move in the tangential direction of the interface, electrostaticforce is concentrated on the central portion of the interface, thusjetting a droplet. However, because the interface and a jetting modevary depending on the level of applied voltage and the electricalconductivity, the surface tension coefficient or the viscosity of fluid,if consecutive signals are applied, only under the restrictive conditionthat a single droplet is formed can droplets be formed and jetted.

To overcome this, if DC voltage is applied, because electrostatic forceis applied to the interface of a droplet only for a limited time, adesired number of droplets can be formed and jetted at a desired pointin time. In the case of a continuous jet or cone-jet, a droplet can alsobe formed by cutting the continuous jet. However, in even this case, toeffectively form a droplet, conditions such as the applied voltage mustbe optimally given depending on the physical characteristics of thefluid. In other words, optimal voltage and frequency pulse must beapplied depending on the characteristics of the fluid such that adesired number of droplets are formed at a desired point in time.

Meanwhile, according to recent research concerning electrospray, it isreported that the interface of fluid can also be changed by AC voltage.Therefore, in the second and third embodiments of the present invention,it is proposed to form and jet a droplet using AC voltage.

Moreover, to enhance the efficiency and effects of forming and jetting adroplet, preferably, DC voltage is applied within a range in which fluidis not sprayed or a droplet is not formed and, simultaneously, ACvoltage of a special frequency is applied. Then, droplets can be formedand jetted a number of times proportional to the correspondingfrequency, and more reliable optimal conditions can be given.

FIG. 17 is a view showing an interface of fluid formed on the pointedend of the nanotip of the droplet jetting apparatus, according to thesecond or third embodiments of the present invention. As shown in (a),(b), (c) and (d), the interface of fluid may be formed into variousshapes. The shapes shown in (a) or (b) are optimal.

Meanwhile, in place of the cantilever 440 including the nanoplate 442and the nanotip 444 provided under the first end of the nanoplate 442 asshown in FIG. 18, a nanoplate 442 which has a pointed end 444 a on anend thereof such that the width of the nanoplate 442 is reduced towardsthe end thereof may be used.

In other words, the other components, such as the second electrode 420,the power supply 500, the control unit 600, etc., remain the same as thesecond or third embodiment. Unlike the cantilever 440 of the second orthird embodiment, the nanotip 444 is integrated with the nanoplate 442and the pointed end 444 a is formed by reducing the width of the end ofthe nanoplate 442. A droplet of fluid is jetted through the pointed end444 a formed on the nanoplate 442. In this case, the nanoplate 442 maybe formed in either micro- or nano-scale.

Although the preferred embodiments of the present invention have beendisclosed with reference the attached drawings for illustrativepurposes, those skilled in the art will appreciate that variousmodifications, additions and substitutions are possible, withoutdeparting from the scope and spirit of the invention as disclosed in theaccompanying claims.

INDUSTRIAL APPLICABILITY

As described above, the present invention provides a droplet jettingapparatus in which a controllable electrostatic field is applied to asurface of fluid jetted through a nozzle, so that the fluid can bejetted in a droplet shape without it undergoing a thermal change.Furthermore, jetted droplets can be precisely controlled using first,second and third electrodes.

In addition, according to an embodiment of the present invention, eventhough several droplet jetting apparatuses are disposed adjacent to eachother at regular intervals, because the present invention is free fromthermal problems which have been experienced with the conventionaltechniques, a highly integrated structure can be realized.

Meanwhile, in a droplet jetting apparatus using a nanotip according tothe present invention, a controllable electrostatic field is applied toa surface of fluid jetted through a pointed end of a nanotip, so thatthe fluid can be jetted in a droplet shape without any accompanyingthermal change. Furthermore, droplets to be jetted can be preciselycontrolled using first, second and third electrodes.

As well, according to an embodiment of the present invention, eventhough several droplet jetting apparatuses using nanotips be disposedadjacent to each other at regular intervals, because the presentinvention is free from thermal problems which have been experienced withthe conventional techniques, a highly integrated structure can berealized.

The invention claimed is:
 1. An apparatus for jetting a droplet using ananotip a first surface of a printable matter, comprising; a main bodyincluding; a cantilever having a nanoplate and a nanotip provided undera lower surface of a first end of the nanoplate; a horizontal openchannel extending from a chamber, formed in a second end of thenanoplate, to the first end of the nanoplate along an upper surface ofthe nanoplate so that fluid contained in the chamber is moved to thefirst end of the nanoplate through the horizontal open channel; avertical open channel formed in one surface of the nanotip such that afirst end thereof communicates with the horizontal open channel and asecond end thereof extends to a pointed end of the nanotip so that thefluid that is moved to the first end of the nanoplate is moved to thepointed end of the nanotip through the vertical open channel; and afirst electrode provided on at least one predetermined portion to makeelectrical contact with the fluid; a second electrode provided betweenthe pointed end of the nanotip and the printable matter, the secondelectrode having therein a through hole, through which a droplet of thefluid is jetted from the pointed end onto the first surface of theprintable matter; a power supply to supply a voltage to be appliedbetween the first electrode and the second electrode; and a control unitto control the power supply.
 2. The apparatus according to claim 1,further comprising: a third electrode disposed at a position spacedapart from a second surface of the printable matter by a predetermineddistance.
 3. The apparatus according to claim 2, wherein the powersupply supplies a voltage to be applied between the first electrode andthe third electrode.
 4. The apparatus according to claim 1, wherein thesecond electrode is formed by alternately placing electrode layers andinsulation layers on top of one another.
 5. The apparatus according toclaim 4, wherein the control unit individually controls a voltageapplied between the first electrode and each of the electrode layers ofthe second electrode.
 6. The apparatus according to claim 1, wherein thevoltage applied between the first electrode and the second electrodecomprises one selected from among a DC-pulse voltage, an AC voltage anda combination of a DC voltage and an AC voltage.
 7. The apparatusaccording to claim 1, wherein a hydrophobic film is applied to a surfaceof the pointed end of the nanotip.
 8. The apparatus according to claim1, wherein the cantilever is made of a polymer material.
 9. An apparatusfor jetting a droplet using a nanotip onto a first surface of aprintable matter, comprising: a main body including: a cantilever havinga nanoplate and a nanotip provided under a lower surface of a first endof the nanoplate; a horizontal open channel extending from a chamber,formed in a second end of the nanoplate, to the first end of thenanoplate along an upper surface of the nanoplate so that fluidcontained in the chamber is moved to the first end of the nanoplatethrough the horizontal open channel; a vertical closed channel formedthrough the nanotip in a vertical direction such that a first endthereof communicates with the horizontal open channel and a second endthereof extends to a pointed end of the nanotip so that the fluid thatis moved to the first end of the nanoplate is moved to the pointed endof the nanotip through the vertical closed channel; and a firstelectrode provided on at least one predetermined portion for makingelectrical contact with the fluid; a second electrode provided betweenthe pointed end of the nanotip and the printable matter, the secondelectrode having therein a through hole, through which a droplet of thefluid is jetted from the pointed end onto the first surface of theprintable matter; a power supply to supply a voltage to be appliedbetween the first electrode and the second electrode; and a control unitto control the power supply.
 10. The apparatus according to claim 9,further comprising: a third electrode disposed at a position spacedapart from a second surface of the printable matter by a predetermineddistance.
 11. The apparatus according to claim 10, wherein the powersupply supplies a voltage to be applied between the first electrode andthe third electrode.
 12. The apparatus according to claim 9, wherein thesecond electrode is formed by alternately placing electrode layers andinsulation layers on top of one another.
 13. The apparatus according toclaim 12, wherein the control unit individually controls a voltageapplied between the first electrode and each of the electrode layers ofthe second electrode.
 14. The apparatus according to claim 9, whereinthe voltage applied between the first electrode and the second electrodecomprises one selected from among a DC-pulse voltage, an AC voltage anda combination of a DC voltage and an AC voltage.
 15. The apparatusaccording to claim 9, wherein a hydrophobic film is applied to a surfaceof the pointed end of the nanotip.
 16. The apparatus according to claim9, wherein the cantilever is made of a polymer material.
 17. Theapparatus according to claim 9, wherein the main body comprises aplurality of main bodies provided adjacent to each other to form anintegrated structure, and the second electrode is provided between theprintable matter and the pointed ends of the main bodies, with throughholes formed in the second electrode at respective positionscorresponding to the pointed ends of the main bodies.
 18. An apparatusfor jetting a droplet using a nanotip onto a first surface of aprintable matter, comprising: a main body including: a nanoplate havinga pointed end formed by reducing a width of a first end of thenanoplate; a horizontal open channel extending from a chamber, formed ina second end of the nanoplate, to the first end of the nanoplate alongan upper surface of the nanoplate so that fluid contained in the chamberis moved to the pointed end of the first end of the nanoplate throughthe horizontal open channel; and a first electrode provided on a portionof the horizontal open channel for making electrical contact with thefluid; a second electrode provided between the pointed end of thenanoplate and the printable matter, the second electrode having thereina through hole, through which a droplet of the fluid is jetted from thepointed end of the nanoplate onto the first surface of the printablematter; a power supply to supply a voltage to be applied between thefirst electrode and the second electrode; and a control unit to controlthe power supply.
 19. The apparatus according to claim 18, furthercomprising: a third electrode disposed at a position spaced apart from asecond surface of the printable matter by a predetermined distance. 20.The apparatus according to claim 19, wherein the power supply supplies avoltage to be applied between the first electrode and the thirdelectrode.
 21. The apparatus according to claim 18, wherein the secondelectrode is formed by alternately placing electrode layers andinsulation layers on top of one another.
 22. The apparatus according toclaim 21, wherein the control unit individually controls a voltageapplied between the first electrode and each of the electrode layers ofthe second electrode.
 23. The apparatus according to claim 18, whereinthe voltage applied between the first electrode and the second electrodecomprises one selected from among a DC-pulse voltage, an AC voltage anda combination of a DC voltage and an AC voltage.
 24. The apparatusaccording to claim 18, wherein a hydrophobic film is applied to asurface of the pointed end of the nanoplate.
 25. The apparatus accordingto claim 18, wherein the nanoplate is made of a polymer material. 26.The apparatus according to claim 18, wherein the nanoplate comprises aplurality of nanoplates provided adjacent to each other to form anintegrated structure, and the second electrode is provided between theprintable matter and the pointed ends of the nanoplates, with throughholes formed in the second electrode at respective positionscorresponding to the pointed ends of the nanoplates.